The present disclosure relates to an image display apparatus for displaying an image on a display device, such as a liquid-crystal display panel, etc. Also, the present disclosure relates to a method of driving an image display apparatus, a grayscale conversion program, and a grayscale conversion apparatus.
For example, for a display device of a mobile electronic device, such as a mobile telephone or a mobile information terminal, or a display device of a personal computer or a television receiver, etc., a liquid-crystal display panel of a monochrome display or a color display, an electroluminescence display panel using electroluminescence of an inorganic material or an organic material, or a plasma display panel, etc., is used.
In the case where grayscale display ability of display device pixels is low, to put it another way, in the case where the number of grayscales of pixels is small, contour lines occur in an image, and thus image quality is deteriorated. In such a case, it is noted that image quality is improved using an error diffusion method.
In an error diffusion method, errors that occurred at the time of converting multivalued image data into binary image data, for example, (that is to say, differences between multivalued image data and binary image data) are “diffused” into a plurality of adjacent pixels with weighting factors (refer to R. W. Floyd and L. Steinberg, An adaptive algorithm for spatial grayscale, Journal of the Society for Information Display vol. 17, no. 2 pp 75-77, 1976). For example, by a typical Floyd-Steinberg method among error diffusion methods, as illustrated in FIGS. 4A and 4B, errors are diffused into a pixel located immediately after a current pixel and three pixels located in a first line lower than the current pixel. By the error diffusion method, it is possible to minimize errors that occurred between original multivalued image and, for example, binary halftone image in an averaged manner, and thus to generate a halftone image having an excellent image quality.